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docs: configuration: update docs on "settings" after the latest changes

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George Kiagiadakis
2024-03-13 18:11:49 +02:00
parent 95cfa9e453
commit e0192789e9
1 changed files with 47 additions and 22 deletions
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docs/rst/daemon/configuration/configuration_option_types.rst
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@@ -18,20 +18,23 @@ booleans, integers, strings, etc. and are all located under the
``wireplumber.settings`` section in the configuration file. Their purpose is to
allow the user to change simple behavioral aspects of WirePlumber.
When WirePlumber starts, the ``metadata.sm-settings`` component (provided by
``module-settings``) reads this section from the configuration file and
populates the ``sm-settings`` metadata object, which is exported to PipeWire.
Then the rest of the components read their configuration options from this
metadata object.
This use of a metadata object allows users to dynamically change the
configuration options at runtime using the ``pw-metadata`` command line tool.
For example, setting the ``device.routes.default-sink-volume`` setting to
``0.5`` can be done like this:
As the name suggests, these options are dynamic and can be changed at runtime
using ``wpctl`` or the :ref:`settings_api` API. For example, setting the
``device.routes.default-sink-volume`` setting to ``0.5`` can be done like this:
.. code-block:: bash
$ pw-metadata -n sm-settings 0 device.routes.default-sink-volume 0.5
$ wpctl settings device.routes.default-sink-volume 0.5
Under the hood, when WirePlumber starts, the ``metadata.sm-settings`` component
(provided by ``libwireplumber-module-settings``) reads this section from the
configuration file and populates the ``sm-settings`` metadata object, which is
exported to PipeWire. In addition, it reads the ``wireplumber.settings.schema``
section and populates the ``schema-sm-settings`` metadata object, which is used
by the API to validate the settings. Any options that are missing from
``wireplumber.settings`` are also populated in ``sm-settings`` from their
default values in the schema. Then the rest of the components read their
configuration options from this metadata object via the :ref:`settings_api` API.
Most of the components that use such dynamic options make sure to listen
to changes in the metadata object so that they can immediately adapt their
@@ -41,21 +44,43 @@ affect created objects in a way that cannot be changed after the object has been
created, so when the option is changed it applies only to new objects and not
existing ones.
Note that the above command will only change the option at runtime, so the
setting won't be restored if wireplumber is restarted. However, you can make the
change persistent by setting the option in the ``persistent-sm-settings`` metadata
object, like this:
Changing the settings at runtime in the ``sm-settings`` metadata object is
a non-persistent change. The changes will be lost when WirePlumber is
restarted. However, the :ref:`settings_api` API also supports saving settings
to a state file, which will be loaded again when WirePlumber starts and
override the settings from the configuration file. This is done by using yet
another metadata object called ``persistent-sm-settings``. When a setting is
changed in the ``persistent-sm-settings`` metadata object, WirePlumber
automatically saves the change to the state file and also changes the value in
the ``sm-settings`` metadata object immediately.
To make such a persistent change using ``wpctl``, the ``--save`` option can be
used. For example, to set the ``device.routes.default-sink-volume`` setting to
``0.5`` and save it to the state file:
.. code-block:: bash
$ pw-metadata -n persistent-sm-settings 0 device.routes.default-sink-volume 0.5
$ wpctl settings --save device.routes.default-sink-volume 0.5
When using the ``persistent-sm-settings`` metadata object, the change will always
be saved in the persistent settings state file. When WirePlumber starts, such
saved setting will have preference over the ones from the configuration file
when populating the ``sm-settings`` metadata object. Also, any changes done in
the ``persistent-sm-settings`` metadata will be reflected in the ``sm-settings``
metadata object as well.
With ``wpctl``, it is also possible to restore a setting to its default value
(taken from the schema), by using the ``--reset`` option. For example, to reset
the ``device.routes.default-sink-volume`` setting, the following command can be
used:
.. code-block:: bash
$ wpctl settings --reset device.routes.default-sink-volume
In addition, the ``--delete`` option can be used to delete a setting from the
``persistent-sm-settings`` metadata object, which will also remove it from the
state file. After deleting, the value from the ``wireplumber.settings`` section
of the configuration file will be used again. For example, to delete the
``device.routes.default-sink-volume`` setting, the following command can be
used:
.. code-block:: bash
$ wpctl settings --delete device.routes.default-sink-volume
A list of all the available settings can be found in the :ref:`config_settings`
section.